Bis(trimethylsilyl)amide und -methanide des Yttriums — Molekülstrukturen von Tris(diethylether-O)lithium-(μ-chloro)-tris[bis(trimethylsilyl) methyl]yttriat,solvensfreiem Yttrium-tris[bis(trimethylsilyl)amid] sowie dem Bis(benzonitril)-Komplex

Bis(trimethylsilyl)amides and -methanides of Yttrium — Molecular Structures of Tris(diethylether-O)lithium-(μ-chloro)-tris[bis(trimethylsilyl)methyl]yttriate, solvent-free Yttrium Tris[bis(trimethylsilyl)amide] as well as the Bis(benzonitrile) Complex The reaction of yttrium(III) chloride with the three-fold molar amount of LiE(SiMe₃)₂ (E = N, CH) yields the corresponding yttrium derivatives. Yttrium tris-[bis(trimethylsilyl)amide] crystallizes in the space group P3 1c with a = 1 636,3(2), c = 849,3(2) pm, Z = 2. The yttrium atom is surrounded trigonal pyramidal by three nitrogen atoms with Y? N-bond lengths of 222 pm. Benzene molecules are incorporated parallel to the c-axes. The compound with E = CH crystallizes as a (Et₂O)₃LiCl-adduct in the monoclinic space group P2₁/n with a = 1 111,8(2), b = 1 865,2(6), c = 2 598,3(9) pm, β = 97,41(3)° and Z = 4. The reaction of yttrium tris[bis(trimethylsilyl)amide] with benzonitrile yields the bis(benzonitrile) complex, which crystallizes in the triclinic space group P1 with a = 1 173,7(2), b = 1 210,3(2), c = 1 912,4(3) pm, α = 94,37(1), β = 103,39(1), γ = 117,24(1)° and Z = 2. The amido ligands are in equatorial, the benzonitrile molecules in axial positions.     

Synthesis and Structure of the Clusters [Hg2(μ—SePh)2(SePh)2(PPh3)2] and [Hg3Br3(μ—SePh)3] · 2 DMSO

The compounds [Hg₂(μ—SePh)₂(SePh)₂(PPh₃)₂] ( I ) and [Hg₃Br₃(μ—SePh)₃] · 2 DMSO ( II ) are formed by reactions of [Hg(SePh)₂] with PPh₃ in THF( I ) or with HgBr₂ in DMSO ( II ) at room temperature. X—ray crystallography reveals that the cluster I consists of a distorted square built by each two Hg and Se atoms. The Hg atoms have almost tetrahedral co‐ordination environments formed by selenium atoms of two (μ‐^—SePh) ligands and Se and P atoms of terminal ^—SePh and PPh₃ ligands. The compound II is a six‐membered ring with alternating Hg and Se atoms in the chair conformation. Two DMSO molecules occupy positions below and above the [Hg₃Se₃] ring with the oxygen atoms directed to the centre of the ring.     

Die Kristallstruktur des N,N′-Bis(trimethylsilyl)imidazoliumiodids [(Me3Si)2(C3H3N2)]+I−

Crystal Structure of N,N′-Bis(trimethylsilyl)-imidazoliumiodide [(Me₃Si)₂(C₃H₃N₂)]⁺I^? Me₃SiI forms with N-Trimethylsiylimidazole (NTMSI) a 1:1 compound which is stable at room temperature. Single crystals can be isolated from a solution of chloroform. The X-ray crystal structure investigation proves an ionic structure.     

Tris[bis(trimethysilyl)amido]zinkate von Lithium und Calcium

Tris[bis(trimethylsilyl)amido]zincates of Lithium and Calcium Calcium-bis[bis(trimethylsilyl)amide] and Bis[bis(trimethylsilyl)amido]zinc yield in 1,2-dimethoxyethane quantitatively Calcium-bis{tris[bis(trimethylsilyl)- amido]zincate} · 3DME. When THF is chosen as a solvent, the two reactants and the zincate form a temperature-independent equilibrium, whereas in benzene no reaction occurs. The tris[bis(trimethylsilyl)amido]zincate anion displays characteristic ¹³C{¹H) and ²⁹Si{¹H] chemical shifts of 7 and ?8 ppm, respectively; the nature of the solvent, the cation and the complexating ligands don't influence the IR nor NMR data of the zincate anion and thus verify that [Ca(DME)₃]²⁺ and {Zn[N(SiMe_{3 2}]₃}^? appear as solvent separated ions, which is also confirmed by their insolubility in hydrocarbons.     

Counter‐anion role in the formation of two supramolecular complexes: [Ag2(DPP)2](ClO4)2·CH3CN and [Ag2(DPP)2(NO3)2] {DPP is N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine}

The title compounds, bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ²N¹:P}disilver bis(perchlorate) acetonitrile monosolvate, [Ag₂(C₁₈H₁₇N₂P)₂](ClO₄)₂·CH₃CN, (1), and bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ²N¹:P}bis[(nitrato‐κ²O,O)silver], [Ag₂(C₁₈H₁₇N₂P)₂(NO₃)₂], (2), each contain disilver macrocyclic [Ag₂(C₁₈H₁₇N₂P)₂]²⁺ cations lying about inversion centres. The cations are constructed by two N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine (DPP) ligands linking two Ag⁺ cations in a head‐to‐tail fashion. In (1), the unique Ag⁺ cation has a near‐linear coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands. Two ClO₄⁻ anions doubly bridge two metallomacrocycles through Ag...O and N—H...O weak interactions to form a chain extending in the c direction. The half‐occupancy acetonitrile molecule lies with its methyl C atom on a twofold axis and makes a weak N...Ag contact. In (2), there are two independent [Ag(C₁₈H₁₇N₂P)]⁺ cations. The nitrate anions weakly chelate to each Ag⁺ cation, leading to each Ag⁺ cation having a distorted tetrahedral coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands, and two chelating nitrate O atoms. Each dinuclear [Ag₂(C₁₈H₁₇N₂P)₂(NO₃)₂] molecule acts as a four‐node to bridge four adjacent equivalent molecules through N—H...O interactions, forming a two‐dimensional sheet parallel to the bc plane. Each sheet contains dinuclear molecules involving just Ag1 or Ag2 and these two types of sheet are stacked in an alternating fashion. The sheets containing Ag1 all lie near x = , , etc, while those containing Ag2 all lie near x = 0, 1, 2 etc. Thus, the two independent sheets are arranged in an alternating sequence at x = 0, , 1, etc. These two different supramolecular structures result from the different geometric conformations of the templating anions which direct the self‐assembly of the cations and anions.     

Synthesis and Characterization of [Hg(sulfamethoxazolato)2]·2DMSO and[Cu2(μ‐CH3CO2)4(sulfamethoxazole)2]

[Hg(sulfamethoxazolato)₂]·2DMSO ( 1 ) and [Cu₂(CH₃COO)₄(sulfa‐methoxazole)₂] ( 2 ) can be obtained by the reaction of sulfamethoxazole with mercury acetate or copper acetate in methanol. The structures of the two complexes were characterized by single crystal X—ray diffractometry. Compound 1 consists of sulfamethoxazolato ligands bridging the metal ions building an unidimensional chain. Two solvent dimethylsulfoxide molecules are involved via N‐H···O hydrogen bridges. The mercury atom shows a linear primary coordination arrangement formed by two trans deprotonated sulfonamidic nitrogen atoms. The overall coordination around the metal atom may be regarded as a strongly distorted octahedron when the interactions of mercury with four sulfonamidic oxygen atoms [bond distances of 2.761(4) Å—2.971(4) Å] are also considered to build an equatorial plane and the N1 and N1′ atoms [bond distance of 2.037(5) Å] occupy the apical positions. Compound 2 is a dinuclear complex in which the copper ions are bridged by four syn‐syn acetate ligands which are related by a symmetry centre located in the centre of the complex. Each copper atom presents a nearly octahedral coordination where the equatorial plane is formed by four oxygen atoms and an isoxazolic nitrogen atom and the second copper atom occupy the apical positions.     

Metallderivate von Molekülverbindungen. IV. Synthese,Struktur und Reaktivität des Lithium-[tris-(trimethylsilyl)silyl]tellanids · DME

Metal Derivatives of Molecular Compounds. IV Synthesis, Structure, and Reactivity of Lithium [Tris(trimethylsilyl)silyl]tellanide · DME Lithium tris(trimethylsilyl)silanide · 1,5 DME [3] and tellurium react in 1,2-dimethoxyethane to give colourless lithium [tris(trimethylsilyl)silyl]tellanide · DME ( 1 ). An X-ray structure determination {-150 · 3·C; P2₁/c; a = 1346.6(4); b = 1497.0(4); c = 1274.5(3) pm; β = 99.22(2)·; Z = 2 dimers; R = 0.030} shows the compound to be dimeric forming a planar Li? Te? Li? Te ring with two tris(trimethylsilyl)silyl substituents in a trans position. Three-coordinate tellurium is bound to the central silicon of the tris(trimethylsilyl)silyl group and to two lithium atoms; the two remaining sites of each four-coordinate lithium are occupied by the chelate ligand DME {Li? Te 278 and 284; Si? Te 250; Li? O 200 pm (2X); Te? Li? Te 105°; Li? Te? Li 75°; O? Li? O 84°}. The covalent radius of 154 pm as determined for the DME-complexed lithium in tellanide 1 is within the range of 155 ± 3 pm, also characteristic for similar compounds. In typical reactions of the tellanide 1 [tris(trimethylsilyl)silyl]tellane ( 2 ), methyl-[tris(trimethylsilyl)silyl]tellane ( 4 ) and bis[tris(trimethylsilyl)silyl]ditellane ( 5 ) are formed.     

The Nitrogen‐Assisted Triphenylphosphine Displacement of 3‐Hydroxypyridine and 3‐Aminopyridine Ligands in Palladium(II) Complexes: Crystal Structures of [Pd(PPh3)Br]2{μ,η2‐C5H3N(OH)}2 and [Pd(PPh3)Br]2{μ,η2‐C5H3N(NH2)}2

Treatment of Pd(PPh₃₎₄ with 2‐bromo‐3‐hydroxypyridine [C₅H₃N(OH)Br] and 3‐amino‐2‐bromopyridine [C₅H₃N(NH₂)Br] in dichloromethane at ambient temperature cause the oxidative addition reaction to produce the palladium complex [Pd(PPh₃₎₂{η¹‐C₅H₃N(OH)}(Br)], 2 and [Pd(PPh₃₎₂{η¹‐C₅H₃N(NH₂)}(Br)], 3 , by substituting two triphenylphosphine ligands, respectively. In dichloromethane solution of complexes 2 and 3 at ambient temperature for 3 days, it undergo displacement of the triphenylphosphine ligand to form the dipalladium complexes [Pd(PPh₃)Br]₂{μ,η²‐C₅H₃N(OH)}₂, 4 and [Pd(PPh₃)Br]₂{μ,η²‐C₅H₃N(NH₂)}₂, 5 , in which the two 3‐hydroxypyridine and 3‐aminopyridine ligands coordinated through carbon to one metal center and bridging the other metal through nitrogen atom, respectively. Complexes 4 and 5 are characterized by X‐ray diffraction analyses.     

Synthesis and Crystal Structure of the Binuclear Complex [Pr2(C10H8N2O4)2(C10H9N2O4)2(H2O)4]·3H2O·C6H6

The binuclear praseodymium(III) complex with N‐(1‐carboxyethylidene)‐salicylhydrazide (C₁₀H₁₀N₂O₄, H₂L) was prepared in H₂O‐C₂H₅OH mixed solution, and the crystal structure of [Pr₂L₂(HL)₂(H₂O)₄]·3H₂O·C₆H₆ was determined by X‐ray single crystal diffraction. The crystal complex crystallizes in the triclinic system with space group P‐1, and in the structure each Pr atom is 9‐coordinated by carboxyl O and acyl O and azomethine N atoms of two tridentate ligands to form two stable five‐membered rings sharing one side in keto‐mode and two water molecules. The coordination polyhedron around Pr³⁺ was described as a monocapped square antiprism geometry. In an individual molecule, four tridentate ligands were coordinated by two negative univalent (HL) and two bivalent forms (L) respectively. Two negative univalent ligands were coordinated via μ₂‐bridging mode.     

Pyrazolat und Tetrazolat als Brückenliganden in [Pt(pz)2]3, [Pt(pz)2]∞ und [Pt(tz)2]∞ Die Kristallstruktur von [Pt(pz)2]3

Pyrazolat and Tetrazolat as Bridging Ligands in [Pt(pz)₂]₃, [Pt(pz)₂]_∞, and [Pt(tz)₂]_∞ Crystal Structure of [Pt(pz)₂]₃ . [Pt(pz)₂(Hpz)₂]₂ (Hpz = pyrazole) suspended in mesitylene decomposes at 185°C in a sealed tube to [Pt(pz)₂]₃ and [Pt(pz)₂]_∞. The reaction of K₂PtCl₄ with K(pz) under hydrothermal conditions at 150°C yields [Pt(pz)₂H₂O]_∞. [Pt(tz)₂ H₂O]_∞ (Htz = tetrazole) is obtained at 25°C from K₂PtCl₄ and Li(tz) in water. [Pt(pz)₂]₃ crystallizes in the tetragonal space group I4₁/a with a = 1694.9 pm, c = 3127.5 pm and Z = 16. It forms a ring structure with the symmetry D_3h. In the structure the Pt atoms are each bridged by two pyrazolato ligands. Short but nonbonding Pt? Pt distances range from 303.4 pm to 306.7 pm. The average Pt? N distance is 201 pm.     

Synthesen und Strukturen neuer amido- und imidoverbrückter Cobaltcluster: [Li(THF)2]3[Co3(μ2-NHMes)3Cl6] (1), [Li(DME)3]2[Co18(μ4-NPh)3(μ3-NPh)12Cl3] (2), [Li(DME)3]2[Co6(μ4-NPh)(μ2-NPh)6(PPh2Et)2] (3) und [Li(THF)4][Co8(μ3-NPh)6(μ2-NPh)3(PPh3)2] (4)

Syntheses and Crystal Structures of new Amido- und Imidobridged Cobalt Clusters: [Li(THF)₂]₃[Co₃(μ₂-NHMes)₃Cl₆] (1), [Li(DME)₃]₂[Co₁₈(μ₄-NPh)₃(μ₃-NPh)₁₂Cl₃] (2), [Li(DME)₃]₂[Co₆(μ₄-NPh)(μ₂-NPh)₆(PPh₂Et)₂] (3), and [Li(THF)₄][Co₈(μ₃-NPh)₆(μ₂-NPh)₃(PPh₃)₂] (4) The reactions of cobalt(II)-chloride with the lithium-amides LiNHMes and Li₂NPh leads to an amido-bridged multinuclear complex [Li(THF)₂]₃[Co₃(μ₂-NHMes)₃Cl₆] ( 1 ) as well as to the imido-bridged cobalt cluster [Li(DME)₃]₂[Co₁₈(μ₄-NPh)₃(μ₃-NPh)₁₂Cl₃] ( 2 ). In the presence of tertiary phosphines two imido-bridged cobalt clusters [Li(DME)₃]₂[Co₆(μ₄-NPh)(μ₂-NPh)₆(PPh₂Et)₂] ( 3 ) and [Li(THF)₄][Co₈(μ₃-NPh)₆(μ₂-NPh)₃(PPh₃)₂] ( 4 ) result. The structures of 1 – 4 were characterized by X-ray single crystal structure analysis.     

meso‐Bis{η5‐1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienyl}iron(II) and the cobalt(II) analogue

The two title crystalline compounds, viz.meso‐bis{η⁵‐1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienyl}iron(II), [Fe(C₁₂H₂₀NSi)₂], (II), and meso‐bis{η⁵‐1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienyl}cobalt(II), [Co(C₁₂H₂₀NSi)₂], (III), were obtained by the reaction of lithium 1‐[1‐(dimethylamino)ethenyl]‐3‐(trimethylsilyl)cyclopentadienide with FeCl₂ and CoCl₂, respectively. For (II), the trimethylsilyl‐ and dimethylaminoethenyl‐substituted cyclopentadienyl (Cp) rings present a nearly eclipsed conformation, and the two pairs of trimethylsilyl and dimethylaminoethenyl substituents on the Cp rings are arranged in an interlocked fashion. In the case of (III), the same substituted Cp rings are perfectly staggered leading to a crystallographically centrosymmetric molecular structure, and the two trimethylsilyl and two dimethylaminoethenyl substituents are oriented in opposite directions, respectively, with the trimethylsilyl group of one Cp ring and the dimethylaminoethenyl group of the other Cp ring arranged more closely than in (II).     

Tris(trimethylsilyl)silylamin und seine lithiierten und silylierten Derivate — Kristallstruktur des dimeren Lithium-trimethylsilyl-[tris(trimethylsilyl)silyl]amids

Tris(trimethylsilyl)silylamine and the lithiated and silylated Derivatives — X-Ray Structure of the dimeric Lithium Trimethylsilyl-[tris(trimethylsilyl)silyl]amide The ammonolysis of the chlor, brom or trifluormethanesulfonyl tris(trimethylsilyl)silane yields the colorless tris(trimethylsilyl)silylamine, destillable at 51°C and 0.02 Torr. The subsequent lithiation, reaction with chlor trimethylsilane and repeated lithiation lead to the formation of lithium tris(trimethylsilyl)silylamide, trimethylsilyl-[tris(trimethylsilyl)silyl]amine and finally lithium trimethylsilyl-[tris(trimethylsilyl)silyl]amide, which crystallizes in the monoclinic space group P2₁/n with a = 1 386.7(2); b = 2 040.2(3); c = 1 609.6(2) pm; β = 96.95(1)° and Z = 4 dimeric molecules. The cyclic Li₂N₂ moiety with Li? N bond distances displays a short transannular Li …? Li contact of 229 pm. The dimeric molecule shows nearly C₂-symmetry, so that one lithium atom forms agostic bonds to both the trimethylsilyl groups, the other one to the tris(trimethylsilyl)silyl substituents. However, the ⁷Li{¹H}-NMR spectrum displays a high field shifted singlet at —1.71 ppm. The lithiation of trimethylsilyl-[tris(trimethylsilyl)silyl]amine leads to a high field shift of the ²⁹Si{¹H} resonance of about 12 ppm for the Me₃SiN group, whereas the parameters of the tris(trimethylsilyl)silyl ligand remain nearly unaffected.     

(PPh4)2[MoN(N3)3Cl]2; Synthese,IR-Spektrum und Kristallstruktur

(PPh₄)₂[MoN(N₃)₃Cl]₂; Synthesis, IR Spectrum, and Crystal Structure The title compound is formed in the reaction of molybdenum (II) benzoate with trimethylsilyl azide and PPh₄Cl in dichloro methane forming dark red single crystals. A PPh₃Me⊕ salt of the ion [MoN(N₃)₃Cl]₂^2? is obtained from (PPh₃Me)₂MoNCl₄] treated with silver azide in CH₂Cl₂ suspension. The solvent CH₂Cl₂ participates in both reactions as oxidizing agent. (PPh₄)₂[MoN(N₃)₃Cl₂ is characterized by a structural analysis based upon X-ray data: space group P1 , Z = 1, a = 1050.7 pm; b = 1185.4 pm; c = 1190.8 pm; α = 98.90°; β = 106.87°; γ = 103.97° (4505 independent, observed reflexions, R = 0.039). The compound consists of PPh₄⊕ cations and centrosymmetric anions [MoN(N₃)₃Cl₂^2? in which the molybdenum atoms are bridged by the N_α atoms of two azide groups; the resulting Mo? N bond lengths are 208 pm and 260 pm. In trans position to the long Mo? N bond the terminal nitrido ligand is situated, the Mo?N distance of 164 pm corresponds to a triple bond. Two terminal azido ligands and the chloro ligand are filling up the coordination sphere of the molybdenum atoms to a coordination number of six. The i.r. spectrum is reported and assigned.     

Direct Syntheses of Bis(tetraphenylphosphonium) and Bis(ethyltriphenylphosphonium) Hexabromo‐diselenates(II), [PPh4]2[Se2Br6] and [PEtPh3]2[Se2Br6]. The Crystal Structure of [PEtPh3]2[Se2Br6]

Brown crystals of [PPh₄]₂[Se₂Br₆] ( 1 ) and [PEtPh₃]₂[Se₂Br₆] ( 2 ) were obtained when selenium and bromine reacted in acetonitrile solution in the presence of tetraphenylphosphonium bromide and ethyltriphenylphosphonium bromide, respectively. The crystal structure of 2 has been determined by X‐ray methods and refined to R = 0.0420 for 4161 reflections. The crystals are monoclinic, space group P2₁/n with Z = 2 and a = 13.055(3) Å, b = 12.628(3) Å, c = 13.530(3) Å, β = 92.40(3)° (293(2) K). In the solid state structure of 2 the dinuclear hexabromo‐diselenate(II) anion is centrosymmetric and consists of two distorted almost square‐planar SeBr₄ units sharing a common edge through two bridging Br atoms. The terminal Se^II–Br bond distances are found to be 2.419(1) and 2.445(1) Å, the bridging μBr–Se^II bond distances 2.901(1) and 2.802(1) Å.     

Cobalt Chalcogenide Clusters. Synthesis,Characterization and DFT Calculations of [Co4Se2(CO)10] and [Co4Te2(CO)11]. Crystal Structure of [Co8Se4(CO)16(μ‐dppa)2]

The reactions of [Co₂(CO)₈] with E(SiMe₃)₂ (E = Se, Te) in CH₂Cl₂ result in the formation of the compounds [Co₄Se₂(CO)₁₀]> ( 1 ) and [Co₄Te₂(CO)₁₁] ( 2 ), respectively. Both cluster complexes have similar molecular structures in which the cobalt atoms form four‐membered rings with μ₄‐bridging chalcogen atoms (Se and Te) above and below the plane of the metal atoms and the carbonyl ligands as either terminal or μ₂‐bridging ligands. DFT‐calculations for both compounds have been carried out in order to obtain some more information about their electronic distribution. In the presence of the phosphine Ph₂PC≡CPPh₂ (dppa), the reaction of [Co₂(CO)₈] with Se(SiMe₃)₂ leads to the formation of [Co₈Se₄(CO)₁₆(μ‐dppa)₂] ( 3 ). During the reaction two molecules of [Co₂(CO)₈] have been added to the acetylene groups of the dppa ligands, whilst the remaining cobalt atoms coordinate to the phosphorus atoms of the phosphine. In this compounds the selenium atoms act as μ₃‐ligands, bridging the metal atoms bonded to the phosphorus with those bonded to the acetylene groups.     

Reaction of Selenium with Bromine in the Presence of Methyltriphenylphosphonium Bromide: Syntheses and Crystal Structures of [PMePh3]2[Se2Br6] and [PMePh3]2[SeBr6(SeBr2)2]

The brown crystals of [PMePh₃]₂[Se₂Br₆] ( 1 ) and red crystals of [PMePh₃]₂[SeBr₆(SeBr₂)₂] ( 2 ) were obtained when selenium and bromine reacted in the solution of acetonitrile in the presence of methyltriphenylphosphonium bromide. The crystal structures of 1 and 2 has been determined by the X‐ray methods and refined to R = 0.0373 for 2397 reflections and 0.0397 for 3417 reflections, respectively. The salt 1 crystallizes in the monoclinic space group P2₁/n with the cell dimensions a = 13.202(5) Å, b = 11.954(4) Å, c = 13.418(6) Å, β = 93.08(4)° (193(2)). The crystals of 2 are triclinic, space group with the cell dimensions a = 10.266(3) Å, b = 11.311(3) Å, c = 11.619(2) Å, α = 108.87(2)°, β = 105.72(2)°, γ = 99.40(2)° (193(2) K). In the solid state structure of 1 the dinuclear hexabromo‐diselenate(II) anion is centrosymmetric and consists of two distorted almost square planar SeBr₄ units sharing a common edge through two μ‐bridging Br atoms. The terminal Se^II–Br bonds are 2.3984(11) and 2.4273(11) Å, whereas the bridging μBr–Se^II bonds are 2.7817(11) and 2.9081(12) Å. In the solid state the trinuclear [SeBr₆(SeBr₂)₂]^2? anion of 2 is centrosymmetric too and contains a nearly regular [SeBr₆] octahedron where the four equatorial bromo ligands each have developed bonds to the Se^II atoms of the SeBr₂ molecules. The contacts between the bridging bromo and the Se^II atoms of the SeBr₂ molecules are 3.0603(15) and 3.1043(12) Å, and can be interpreted as bonds of the donor‐acceptor type with the bridging bromo ligands as donors and the SeBr₂ molecules as acceptors. The Se^IV–Br distances are in the range 2.5570(9)–2.5773(11) Å and the Se^II–Br bond lengths in coordinated SeBr₂ molecules – 2.3411(12) and 2.3421(10) Å.     

Two‐Dimensional Holo‐ and Hemidirected Lead(II) Coordination Polymers: Synthetic,Spectroscopic, Thermal,and Structural Studies of [Pb(μ‐SCN)2(μ‐ebp)1.5]n and {[Pb(μ‐OAc)(μ‐ebp)](ClO4)}n (ebp=4,4′‐[(1E)‐Ethane‐1,2‐diyl]bis[pyridine]; OAc=Acetato)

Two new coordination polymers of Pb^II complexes with bridging 4,4′‐[(1E)‐ethane‐1,2‐diyl]bis[pyridine] (ebp), thiocyanato, and acetato ligands, [Pb(μ‐SCN)₂(μ‐ebp)_1.5]_n ( 1 ) and {[Pb(μ‐OAc)(μ‐ebp)](ClO₄)}_n ( 2 ), were synthesized and characterized by elemental analysis, FT‐IR, ¹H‐ and ¹³C‐NMR, thermal analysis, and single‐crystal X‐ray diffraction. In 1 , the Pb²⁺ ions are doubly bridged by both the ebp and the SCN⁻ ligands into a two‐dimensional polymeric network. The seven‐coordinate geometry around the Pb²⁺ ion in 1 is a distorted monocapped trigonal prism, in which the Pb²⁺ ions have a less‐common holodirected geometry. In 2 , the Pb²⁺ ions are bridged by AcO⁻ ligands forming linear chains, which are also further bridged by the neutral ebp ligands into a two‐dimensional polymeric framework. The Pb²⁺ ions have a five‐coordinate geometry with two N‐atoms from two ebp ligands and three O‐atoms of AcO⁻. Although ClO acts as a counter‐ion, it also makes weak interactions with the Pb²⁺ center. The arrangement of the ligands in 2 exhibits hemidirected geometry, and the coordination gap around the Pb²⁺ ion is possibly occupied by a configurationally active lone pair of electrons.     

Syntheses and structures of Tetranuclear Cluster complexes of molybdenum [Mo4(μ3-S)2(μ2-S)4 X 2-(PMe3)6] (X = SH,Cl, Br,I, SCN) and [Mo4(μ3-S)2-(μ2-S)4 (dtc)2(PMe3)4] (dtc = diethyldithiocarbamate)

A molybdenum cluster complex [Mo₄(μ₃-S)₂(μ₂-S)₄)(SH)₂(PMe_{3 6}] has been synthesized by the reaction of (NH₄)₂Mo₃S₁₃ with trimethylphosphine. The cluster core is composed of four molybdenum atoms arranged in the rhombus bridged by two capping and four bridging sulfur atoms. Two SH and six tri-methylphosphine ligands are coordinated to the terminal positions. The mean oxidation stares of molybdenum is +3.5 and there are five Mo-Mo bonds consistent with ten metal cluster electrons. The complex has been converted into [Mo₄(μ₃-S)₂(μ₂-S)₄ X ₂(PMe₃)₆] (X=Cl, Br, I, SCN) and [Mo₄μ₃-S₂(μ₂-S)₄ (die)₂(PMe₃)₄] (dtc - diethyldithiocarbamate). In the case of the dtc complex, two terminal trimetlaylphosphine ligands are displaced and dtc ligands are coordinated in chelate fashion. The structures of the SH, Cl, Br, and dtc complexes have been determined by X-ray crystallography. Molecular orbital calculations with DV-Xα method has shown large HOMO-LUMO gaps (1.52-1.74eV) for [Mo₄S₆ X ₂(PH₃)₄] (X= SH, Cl, and Br).     

Synthesis and Crystal Structure of Bis(methyltriethylammonium) Hexabromotellurate(IV)‐tris{dibromodiselenate(I)}, [NMeEt3]2n[TeBr6(Se2Br2)3]n,Containing a Chain‐Polymeric Mixed‐valence Bromotellurate(IV)‐Selenate(I) Anion

Red crystals of [NMeEt₃]_2n[TeBr₆(Se₂Br₂)₃]n ( 1 ) were isolated when selenium and bromine (1:1) were allowed to react in acetonitrile solution in the presence of tellurium(IV) bromide and methyltriethylammonium bromide (1:2). The salt 1 crystallizes in the monoclinic space group C2/c with the cell dimensions a = 27.676(6) Å, b = 9.665(2) Å, c = 18.796(4) Å and ß = 124.96(3)° (120 K). The [TeBr₆(Se₂Br₂)₃]^2— anions contain nearly regular octahedral [TeBr₆]^2— ions which are incorporated into a polymeric chain by bonding contacts between 3 facial bromo ligands and 3 Se₂Br₂ molecules, one of which is situated on the twofold symmetry axis. The distances between the μBr ligands and the Se^I atoms of the Se₂Br₂ molecules are observed in the range 3.308(2) — 3.408(2) Å and can tentatively be interpreted as donor‐acceptor bonds with μBr as donors and Se₂Br₂ as acceptors. The Te^IV—Br distances are in the range 2.669(1) — 2.687(1) Å. The bond lengths in the connecting Se₂Br₂ molecules are: Se^I—Se^I = 2.267(2) and 2.281(2) Å, Se^I—Br = 2.340(1), 2.353(1) and 2.337(1) Å.